Health monitoring systems and methods

ABSTRACT

Systems, methods and devices for reducing noise in health monitoring including monitoring systems, methods and/or devices receiving a health signal and/or having at least one electrode or sensor for health monitoring.

BACKGROUND

Advances in software, electronics, sensor technology and materialsscience have revolutionized patient monitoring technologies. Inparticular, many devices and systems are becoming available for avariety of health monitoring applications. However, improvements may yetbe desired for health monitoring devices and systems that provide one ormore of effective data collection and/or manipulation for parameterdetermination.

Further alternatives for patients and their physicians may then bedeveloped to include robust and convenient monitors that in someinstances may collect and transfer long-term data as well as monitorevents in real-time, including multi-variable parameter determination.

SUMMARY

Described herein are several alternative medical monitoring devices,systems and/or methods for parameter determination, in some instancesfor long-term sensing and/or recording of cardiac and/or respiratorydata of an individual, such as a neonate, athlete, or cardiac patient. Anumber of alternative implementations and applications are summarizedand/or exemplified herein below and throughout this specification.

In one alternative aspect, the developments hereof may include animplementation wherein a health device is configured for monitoring aplurality of physiological parameters of an individual fromtime-concordant measurements collected by one or a plurality of sensors,including a variety of one or more of, but not limited to, electrodesfor measuring ionic potential changes for electrocardiograms (ECGs), alight source and one or more photodetectors, such as LED-photodiodepairs, for optically based oxygen saturation measurements, a temperaturesensor, an xyz accelerometer for movement and exertion measurements, andthe like. In some implementations, methods and devices of thedevelopments hereof may be used to generate a respiration waveform.Other implementations may include a circuit that mimics a drivenright-leg circuit (sometimes referred to herein as “a proxy drivenright-leg circuit”) that may permit reduction in common mode noise in asmall-footprint device conveniently adhered or having the capacity to beadhered to an individual.

In another alternative aspect hereof, a blood pressure determination maybe made from a determination of pulse transit time. The pulse transittime is the time for the cardiac pressure wave to travel from the heartto other locations in the body. Measurements of pulse transit time maythen be used to estimate blood pressure. Heart beat timing from ECG orotherwise and photoplethysmogram (aka PPG) signals can be used togenerate pulse transit time. Note, such signals may be generated fromconventional or other to-be-developed processes and/or devices orsystems; or, such signals may be taken from one or more wearable healthmonitoring devices such as those also described hereinbelow.

In another alternative aspect, the developments hereof may include oneor more methods and/or devices for measuring and/or determining oxygensaturation parameters from time concordant pulse oximetry signals andECG signals. In one implementation, ECG signals may be used to defineintervals, or “frames” of pulse oximetry data that are collected andaveraged for determining the constant and main periodic components(e.g., DC and AC components) of the pulse oximetry signals from which,in turn, values for oxygen saturation may be determined.Patient-wearable devices of such implementations with pulse oximetry andECG sensors may be particularly useful when placed on a patient's chestfor such signal acquisition.

These as well as other alternative and/or additional aspects areexemplified in a number of illustrated alternative and/or additionalimplementations and applications, some of which are shown in the figuresand characterized in the claims section that follows. However, as willbe understood by the ordinarily skilled artisan, the above summary andthe detailed description below do not describe the entire scope of theinventions hereof and are indeed not intended to describe eachillustrated embodiment or every implementation of the present inventionsnor provide any limitation on the claims or scope of protection hereinset forth below.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings include:

FIG. 1, which includes and is defined by sub-part FIGS. 1A-1K,illustrates several alternatives of the present developments, includinga variety of isometric, top and bottom plan and elevational views ofdevices and alternative conductive adhesive structures.

FIG. 2, which includes and is defined by sub-part FIGS. 2A-2D, providescircuit diagrams of alternatives to, in FIGS. 2A-2C, a driven right legcircuit, and in FIG. 2D, pulse oximetry.

FIG. 3 is a flow chart including alternative methods of use.

FIG. 4 illustrates an exemplary computer system or computing resourceswith which implementations hereof may be utilized.

FIG. 5, which includes and is defined by sub-part FIGS. 5A-5D, providesalternative screenshots of alternative software implementationsaccording hereto.

FIGS. 6A and 6B illustrate features of one embodiment for measuringoxygen saturation using pulse oximetry signals and electrocardiogramsignals.

FIG. 6C is a flow chart showing steps of one embodiment for determiningoxygen saturation values.

FIGS. 6D and 6E illustrate an embodiment for determining depth ofrespiration values.

FIGS. 7A, 7B and 7C set forth flow diagrams for alternativemethodologies hereof.

DETAILED DESCRIPTION

While the inventions hereof are amenable to various modifications andalternative forms, specifics thereof have been shown herein by way ofexample in the drawings and the following description. It should beunderstood, however, that the intention is not to limit the inventionsto the particular embodiments described. The intention is to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the inventions whether described here or otherwise beingsufficiently appreciable as included herewithin even if beyond theliteral words hereof.

In one aspect, a system hereof may include a device for monitoringphysiological parameters such as one or more or all of electrocardiogram(aka ECG or EKG), photoplethysmogram (aka PPG), pulse oximetry,temperature and/or patient acceleration or movement signals.

Moreover, systems hereof may be established to measure and/or processsuch signals of a patient using or including one or more of thefollowing elements: (a) a circuit, sometimes flexible as in or on orforming a flexible or flex circuit board, embedded in or on a flatelastic substrate or board having a top surface and a bottom surface,the circuit having one or more of (i) at least one sensor mounted in oron or adjacent the bottom surface of the flat elastic substrate, the atleast one sensor being capable of electrical or optical communicationwith the patient, (ii) at least one signal processing module forreceiving and/or accepting signals from the at least one sensor in someimplementations also providing for transforming such signals for storageas patient data; (iii) at least one memory module for receiving and/oraccepting and storing patient data, (iv) at least one data communicationmodule for transferring patient data, stored or otherwise to an externaldevice, and (v) a control module for controlling the timing andoperation of the at least one sensor, one or more of the at least onesignal processing module, the at least one memory module, the at leastone data communication module, and/or the control module capable ofreceiving commands to implement transfer of patient data by the at leastone data communication module and to erase and/or wipe patient data fromthe at least one memory module; and (b) a conductive adhesive removablyattached to the bottom surface of the flat elastic substrate, theconductive adhesive capable of adhering to skin of the patient and ofconducting an electrical signal substantially only in a directionperpendicular to the bottom surface of the flat elastic substrate,and/or in some implementations including a conductive portion adjacentthe sensor or sensors and a non-conductive portion. In someimplementations, the conductive adhesive is an anisotropicallyconductive adhesive in that it comprises regions of material thatconducts current substantially only in a direction perpendicular to theskin (i.e. “z-axis” conduction).

In some implementations, devices hereof will be for comprehensivelong-term cardiac monitoring, inter alia. Features of such may includeone or more of a Lead 1 ECG, PPG, pulse oximeter, accelerometer,temperature sensor and/or a button or other indicator for manual patientevent marking. Such a device may be adapted to store up to, for example,about two weeks of continuous data (though more or less will also befeasible in alternative implementations), which may in someimplementations be downloaded to a clinic or other computer in a shorttime period, as for one example, in only about 90 seconds (though moreor less time will be viable in alternative implementations) via computerconnection, whether wireless or wired as in one example by USB or otheracceptable data connection. A companion software data analysis packagemay be adapted to provide automated event capture and/or allow immediateor delayed, local data interpretation.

Intermittent cardiac anomalies are often difficult for physicians todetect and/or diagnose, as they would typically have to occur during aphysical examination of the patient. A device hereof may address thisproblem with what in some implementations may be a continuous orsubstantially continuous monitoring of one or a number of vital signs.

Some alternative features may include one or more of (i) a driven “RightLeg” circuit with electrodes located only on the chest, (ii) a “z-Axis”or anisotropic conductive adhesive electrode interface that may permitelectrical communication only between an electrode and a patient's skinimmediately beneath the electrode, (iii) data transmission to andinterpretation by a local computer accessible to CCU/ICU personnel, (iv)a unique combination of hardware that may allow correlation of multipledata sources in time concordance to aid in diagnosis.

In some alternative implementations, devices and systems hereof mayprovide 1) reusability (in some cases near or greater than about 1000patients) that may allow recouping cost of the device in just about10-15 patient tests; 2) one or more of ECG waveform data, inertialexertion sensing, manual event marking, temperature sensing and/or pulseoximetry, any or all of which in time concordance to better detect andanalyze arrhythmic events; 3) efficient watertightness or waterproofing(for the patient/wearer to be able to swim while wearing the device);and 4) a comprehensive analysis package for typically immediate, localdata interpretation. An alternative device may be adapted to takeadvantage of flex-circuit technology, to provide a device that islight-weight, thin, durable, and flexible to conform to and move withthe patient's skin during patient/wearer movement.

FIGS. 1 and 2 illustrate examples of alternative implementations ofdevices that may be so adapted.

FIG. 1 shows a device 100 that has a component side or top side 101,patient side or circuit side 102, and one or more inner electricallayer(s), generally identified by the reference 103 and an elongatedstrip layer 105. The strip layer 105 may have electronics thereon and/ortherewithin. FIG. 1A shows isometrically these in what may here beconsidered a substantially transparent device together with some otherelements that may be used herewith. FIG. 1B is more specificallydirected to a top side 101 plan view and FIG. 1C to an underside,patient side 102 plan view and FIG. 1D a first elevational, side view.

Many of the electronics hereof may be disposed in the electronics layeror layers 103, and as generally indicated here, the electronics may beencapsulated in a material 104 (see FIGS. 1A, 1B, 1D and 1K for someexamples), medical grade silicone, plastic or the like, or pottingmaterial, to fix them in operative position on or in or otherwisefunctionally disposed relative to the elongated strip layer 105. Thepotting or other material may in many implementations also oralternatively provide a waterproof or watertight or water resistantcoverage of the electronics to keep them operative even in water orsweat usage environments. One or more access points, junctions or otherfunctional units 106 may be provided on and/or through any side of theencapsulation material 104 for exterior access and/or communication withthe electronics disposed therewithin, or thereunder. FIGS. 1A, 1B and 1Dshow four such accesses 106 on the top side. These may include high Zdata communication ports and/or charging contacts, inter alia. Thisupper or component side 101 of device 100 may be coated in a siliconecompound for protection and/or waterproofing, with only, in someexamples, a HS USB connector exposed via one or more ports 106, e.g.,for data communication or transfer and/or for charging.

The elongated strip layer 105 may be or may include a circuit or circuitportions such as electrical leads or other inner layer conductors, e.g.,leads 107 shown in FIG. 1D, for communication between the electronics103 and the electrically conductive pads or contacts 108, 109 and 110described further below (108 and 109 being in some examples, highimpedance/high Z silver or copper/silver electrodes forelectrocardiograph, ECG, and 110 at times being a reference electrode).In many implementations, the strip layer 105 may be or may include flexcircuitry understood to provide acceptable deformation, twisting,bending and the like, and yet retain robust electrical circuitryconnections therewithin. Note, though the electronics 103 and electrodes108, 109, 110 are shown attached to layer 105; on top for electronics103, and to the bottom or patient side for electrodes 108, 109, 110; itmay be that such elements may be formed in or otherwise disposed withinthe layer 105, or at least be relatively indistinguishably disposed inrelative operational positions in one or more layers with or on oradjacent layer 105 in practice. Similarly, the leads or traces 107 areshown embedded (by dashed line representation in FIG. 1D); however,these may be on the top or bottom side, though more likely top side toinsulate from other skin side electrical communications. If initiallytop side (or bottom), the traces may be subsequently covered with aninsulative encapsulant or like protective cover (not separately shown),in many implementations, a flexible material to maintain a flexiblealternative for the entire, or majority of layer 105.

On the patient side 102, the ECG electrodes 108, 109 and 110 may be leftexposed for substantially direct patient skin contact (though likelywith at least a conductive gel applied therebetween); and/or, in manyimplementations, the patient side electrodes 108, 109 and/or 110 may becovered by a conductive adhesive material as will be described below.The electrodes may be plated with or may be a robust high conductivematerial, as for example, silver/silver chloride for biocompatibilityand high signal quality, and in some implementations may be highlyrobust and, for one non-limiting example, be adapted to withstand overabout 1000 alcohol cleaning cycles between patients. Windows or othercommunication channels or openings 111, 112 (FIG. 1C) may be providedfor a pulse oximeter, for example, for LEDs and a sensor. Such openings111, 112 would typically be disposed for optimum light communication toand from the patient skin. An alternative disposition of one or morelight conduits 111 a/112 a (and 111 b/112 b) is shown in a non-limitingexample in FIG. 1D more nearly disposed and/or connected to theelectronics 103. A variety of alternative placements may be usableherein/herewith.

In some implementations, sampling of the ambient light (with the LEDsoff) may be provided, and then subtracting this from each of thepulse-ox signals in order to cancel out the noise caused by sunlight orother ambient light sources.

The LEDs and photodiode sensor may also and/or alternatively be coveredwith a layer of silicone to remove any air gap between the sensor/LEDsand the patient skin. Two examples of such are set forth in respectiveFIGS. 1H and 1K; where a silicone layer or covering 121 is showncovering/surrounding the light conduits and/or sensors/LEDs 111 c/111d/112 c. LED 111 c (FIGS. 1H and 1K) might be a Red LED, LED 111 d(FIGS. 1H and 1K) might be an IR (infrared) LED and the device 112 c(FIGS. 1H and 1K) might be a sensor. This may reduce the light lost toreflection off the skin, and thereby greatly increase the signal andreduce the noise caused by motion of the skin relative to the sensor. Insome implementations this silicone might be referred to as a light pipeand in some situations may be clear, colorless, and/or medical gradesilicone. As described further below, the silicone layer or covering 121may also/alternatively be referred to as a light pipe or lens 121/121a/121 b herein inasmuch as how it may be involved in light transmittingor to be transmitted therethrough, whether upon emission or receivedupon reflection or both.

In one or more implementations, a lens 121/121 a/121 b hereof may bemade from a medical grade silicone that is one or more of clear,colorless, soft, low durometer. Exemplars of such specialized siliconesthat may be used herewith are known as “tacky gels” (several suppliers),and typically have very high-tack adhesives, preferably embedded on bothsides. A low durometer silicone combined with double-sided adhesive onthe tacky gel allows the construction of a lens 121/121 a/121 b that maybe both conforming to the electronic sensors and skin, as well as, insome implementations, exhibiting properties of motion artifact reductionby limiting movement between the skin-lens-sensor interface. A lensaccording hereto may also/alternatively be specially shaped such that itcan be trapped between layers of the composite adhesive strip (see e.g.,alternatives of FIGS. 1D, 1G and 1I and 1J), and in someimplementations, with a raised portion the size of the opening, often arectangular opening, in the adhesive strip that allows the lens toprotrude slightly on the patient side of the adhesive strip (see furtherdetail relative to FIG. 1K, described below).

In FIG. 1K an implementation of a further alternative silicone coveringor encapsulant 121 a for the LEDs and sensor 111 c/111 d/112 c, mayinclude a convex lens at or adjacent the covering external surface 121b. In many implementations, the external surface and lens are one andthe same and/or the lens may be defined by the surface 121 b of theencapsulant material 121 a. What this provides is a structure and methodfor interfacing pulse oximetry LED emitters 111 c/111 d and one or morephotodiode sensors 112 c with the skin surface, whether chest orforehead (e.g., infant or neonate) or otherwise mounted on the patientor user body.

More particularly, as otherwise described herein, a system and/or device100 hereof may utilize one or multiple LED emitters 111 c/111 d ofselected wavelengths and one or multiple photodiode sensors. However, Inorder to maximize coupling of the LED/sensor combination to the skin1001 of a wearer 1000, a lens 121 b comprised of optically clear,medical grade silicone may be molded onto or molded such that it may belater attached in covering relationship on the LED/sensor combination111 c/111 d/112 c. In many implementations, the lens 121 b may bepartially spherical or perhaps hemispherical in nature, though it neednot be. Curvature of other shapes may be useful as well. Curvaturereduces loss of skin contact when the device 100 may be moved, whetherby wearer motion or otherwise. I.e., motion of the wearer 1000 or thedevice 100 relative to the wearer 1000 can result in a quasi-rollingcontact of the lens on and in relation to the skin 1001. Bettermaintained skin contact means better data acquisition withoutinterruption and/or with reduced noise.

Moreover, related to the function of maintaining contact is the lightpiping effect that may be achieved when LEDs and sensors, even ofdifferent heights are communicating without air gap interruption throughthe light pipe of the encapsulant material 121 a. With no air gap fromemitter to and through the light pipe 121 a and with curved surfacesubstantially constant contact with the skin, there is thus no air gapinterruption in transmission into and through and reflected back onreturn from within the skin and back to the sensor via the same lightpipe material 121 a (transmission and reflection both referring to lighttravel). This reduces inefficiencies caused by light wave scattering atair gap interfaces (air gaps allow for light to bounce off the skin orother surface). I.e., encapsulation of the LEDs and the sensor; providesno air-gap and a light pipe effect to and the curved surface provideshigh quality low scattering transmission into the skin and reception ofreflection from the skin and bone. The light pipe and curved lenssurface maintain uninterrupted contact skin and lens reduces lostsignals due skin reflection. The signal to noise ratio goes down anddata acquisition goes up in quality.

Such a lens 121 b may thus serve one or multiple purposes, including insome instances, inter alia: 1) providing a “light-pipe” effect to assureequal or otherwise high quality coupling of the different height LEDsand sensors, as well as substantially constant coupling to the skin toreduce motion artifact; 2) focusing of emitted light through the skin tothe bone; and, 3) focusing of reflected light through the skin to thephotodiode sensors.

As a further note, the radius of the lens may be designed to maximize 1)through 3). The height of the lens is designed to allow it to protrudeabove composite adhesive 113 of the device 100 and into the skin, butnot deep enough to disturb the capillary bed which would also result inbad data. Moreover, the radius of curvature and the angles of LEDlightwave emission are not necessarily highly controlled and need not bebecause the LEDs used to penetrate the skin, e.g., the red and infra-redLEDs; provide a very wide array of angles of emission, and thus a largenumber of reflected array of lightwaves will be focused back to thesensor by a large variety of curved surfaces. I.e., the curved surfaceis helpful for maintaining contact through movement (accidental or onpurpose), and is less important to the angles of transmission throughthe skin and reflection back to the sensor. In other words, manydifferent radii of curvature will be effective with very littledifference in data/wave transmission and reflection; the wide angleemission of LED takes care of what might be a variety of radii. Rather,the curvature may have more limitation in the maintenance of contact dueto movement of the device 100—e.g., flatter curvatures won't rollreadily, and very small radii of curvature will not transmit or receiveas much data.

In some implementations, a radii of curvature found useful have beenbetween about 20 and 40 (both 20.34 mm and 39.94 mm radii of curvaturehave been found useful) for a device having LEDs and sensors in acompartment of about 12.6 mm by 6.6 mm. It may be noted further thatLEDs may be on one side or another or on two opposing sides or perhapsat four or more substantially equi-distant points around a sensor andmay provide desirable results.

Note further, pulse oximetry hereof may be with multiple light sourcesand/or sensors as may be one interpretation of the dispositions of FIGS.1H and 1K. Typical pulse oximetry circuitry uses one light source (LED)per wavelength (typically red, infrared, and others). However, devicesand/or methods hereof may make use of multiple light sources for eachwavelength. This allows interrogation of a wider area of capillary bedin/on the patient/wearer in order to reduce the effects of a localmotion artifact. Similarly, multiple sensors may be used for the samepurpose or advantage.

Furthermore, a combination of driven right leg and/or proxy driven rightleg together with pulse oximetry can provide additional benefits. Theright leg circuit, proxy right leg and/or driven right leg, whether forchest or forehead or other electrode placement, can remove common modeand power line noise that would/might otherwise be capacitively-coupledinto the pulse oximetry sensor and reduce effectiveness thereof. Acombination of driven right leg and/or proxy driven right leg andimproved pulse oximetry with a lens as described in and for FIG. 1K cansignificantly reduce such noise, and thereby enhance data acquisition.For driven electrodes see further detail below.

FIG. 1D provides a first example of an adhesive 113 that may be usedherewith. The adhesive layer 113 is here a double-sided adhesive forapplication to the bottom side 102 of the device 100, and a second side,perhaps with a different type of adhesive for adhering to the skin ofthe human patient (not shown). Different types of materials for adhesionmight be used in that the material of choice to which the adhesive layeris to be attached are different; typically, circuit or circuit boardmaterial for connection to the device 100, and patient skin (notseparately shown) on the patient side. A protective backing 114 may beemployed on the patient side until application to the patient isdesired. Note, in many applications, the adhesive 113 is anisotropic inthat it may preferably be only conductive in a single or substantially asingle direction, e.g., the axis perpendicular to the surface ofadhesive contact. Thus, good electrically conductive contact for signalcommunication can be had through such adhesive to/through the adhesiveto the electrical contacts or electrodes, 108, 109 and 110. Note, acorresponding one or more light apertures 111 b/112 b are shown in theadhesive of 113 of the example of FIG. 1D to communicate lighttherethrough in cooperation with the light conduit(s) 111 a/112 ain/through layer 105 for communication of light data typically involvedin pulse oximetry.

The adhesive may thus be placed or disposed on the device 100, in someimplementations substantially permanently, or with some replaceability.In some implementations, the device as shown in FIGS. 1A-1D and/or 1Gwithout (or with in some implementations) the adhesive may be reusable.In many such cases, the adhesive layer 113 may be removed and replacedbefore each subsequent use, though subsequent re-use of and with a layer113 is not foreclosed. In a first or subsequent use with a replaceableadhesive layer 113, it may be that the user applying the device to thepatient, e.g., the physician or technician or even the patient,him/herself, applies the conductive transfer adhesive 113 to the patientside 102 of the device 100. The protective backing 114 may then beremoved, and the device adhered to the patient and activated.

Activation of the device after application to a patient/wearer may occurin a number of ways; in some, it may be pre-set that an affirmativeactivation interaction may not be necessary from the doctor or patientor like due to either an inertial and/or a pulse oximeter activationwhich may be substantially automatically activating, e.g., uponreceiving sufficient minimum input (movement in case of inertial systemor light reflection of blood flow for pulse oximetry); however, a buttonmay be provided at an access 106 or in some other location adjacent theelectronics to allow the patient to start or stop the device orotherwise mark an event if desired. In one exemplar implementation thedevice may be worn for a period such as two weeks for collection of datasubstantially continuously, or at intervals as may be preferred andestablished in or by the systems hereof.

After a monitoring period is over, a physician, technician, patient orother person may then remove the device from the patient body, in someinstances remove the adhesive, in some instances with alcohol, and mayestablish a data communication connection for data transfer, e.g., bywireless communication or by insertion/connection of a USB or like dataconnector to download the data. The data may then be processed and/orinterpreted and in many instances, interpreted immediately if desired. Apower source on board may include a battery and this can then also berecharged between uses, in some implementations, fully recharged quicklyas within about 24 hours, after which the device could then beconsidered ready for the next patient or next use.

Some alternative conductive adhesives may be used herewith. FIGS. 1E, 1Fand 1G show one such alternative conductive adhesive 113 a; a bottomplan view in FIG. 1E and elevational side views thereof in FIGS. 1F and1G (as being connected to a device 100 in FIG. 1G). In someimplementations, the conductivity may be anisotropic as introducedabove; in some conductive primarily if not entirely in the direction ofthe Z-Axis; perpendicular to the page (into and/or out of the page) inFIG. 1E, and/or vertically or transversally relative to the longhorizontal shown axis of device 100 in the implementation view of FIG.1F.

The implementation of this particular example includes a compositeadhesive 113 a which itself may include some non-conductive portion(s)113 b and some one or more conductive portions 113 c. The adhesivecomposite 113 a may, as described for adhesive 113 above be double sidedsuch that one side adheres to the patient while the other side wouldadhere to the underside 102 of the device 100 (see FIG. 1G) so that oneor more conductive portions 113 c may be disposed or placed inelectrically communicative and/or conductive contact with the integratedelectrodes on the electronic monitoring device 100. Since the electrodeswould operate better where they may be electrically isolated orinsulated from each other, yet each making electrical contact orcommunication with the patient's skin, the adhesive may further be morespecifically disposed in some implementations as follows.

As shown in FIGS. 1E and 1F, three isolated conductive portions 113 cmay be disposed separated from each other by a body portion 113 b whichmay be non-conductive. These could then correspond to the electrodes108, 109, 110 from the above-described examples, and as moreparticularly shown schematically in FIG. 1G (note the scale isexaggerated for the adhesive 113 a and thus, exact matching to theelectrodes of device 100 is not necessarily shown). In some examples,the electrode areas 113 c may be a conductive hydrogel that may or maynot be adhesive, and in some examples, may be made of a conductive anadhesive conductive material such as 3M Corporation 9880 Hydrogeladhesive (3M Company, St. Paul, Minn.). These areas 113 c may then beisolated from each other by a non-conductive material 113 b such as 3MCorporation 9836 tape or 3M double-sided Transfer Adhesive 9917 (3M, St.Paul, Minn.) or equivalent. The additional layer 113 d, if used, mightbe a 3M 9917 adhesive together with the 113 b of a 9836 material. Theseconstructs may provide the effect of creating a low electrical impedancepath in the Z-axis direction (perpendicular to page for FIG. 1E andvertically/transversally for FIGS. 1F and 1G) for the electrode areas113 c, and high electrical impedance path between the electrodes in theX/Y directions. (See FIGS. 1E, 1F and 1G; coplanar with the page in FIG.1E and horizontal and perpendicular to the page in FIGS. 1F and 1G).Thus, a composite adhesive strip can ensure not only device adhering tothe patient, but also that the electrodes whether two or as shown threeelectrodes are conductively connected by conductive portions of theadhesive strip, where the combination of conductive and non-conductiveportions can then reduce signal noise and/or enhance noise freecharacteristics. Electrodes that move relative to skin can introducenoise; that is, electrodes electrically communicative/connected to theskin via a gel may move relative to the skin and thus introduce noise.However, with one or more conductive adhesive portions in a compositeadhesive connected to respective electrodes and then substantiallysecurely connected to the skin will keep the respective electrodessubstantially fixed relative to the skin and thereby reduce or eveneliminate electrode movement relative to the skin. Removal of suchmovement would then remove noise which would thereby provide a cleansignal that can allow for monitoring cardiac P waves which enhances thepossibility to detect arrhythmias that couldn't otherwise be detected.Further description is set forth below.

In some implementations, a further optional connective and/or insulativestructure 113 d may be implemented as shown in FIG. 113d to providefurther structural and insulative separation between electrodes withconnected to a device 100 on the underside 102 thereof (see FIG. 1G).Though shown separate in FIGS. 1F and 1G, it may be contiguous with theinsulative adhesive 113 b of these views.

Further alternatives related to the adhesive may be used. In someimplementations, a composite adhesive strip may be used havingproperties to reduce one or more motion artifacts. Typical ECGattachment systems use a conductive gel located over the electrode.Here, however, a hydrogel adhesive may be used which is embedded in acontinuous sheet of laminated adhesives that cover the selected regionsor the entire footprint of the device. The fact that the hydrogel itselfhas strong adhesive properties coupled with the complete coverage of thedevice with adhesives may assure a strong bond between the device andthe patient's skin. Contributing to motion artifact reduction may be analternative vertical placement of the device on the sternum whichresults in reduced motion artifacts for one or more of ECG signals,photoplethysmography waveforms, and oxygen saturation signals.

In some implementations, composite adhesive improvements may includewater-proof encapsulation of the hydrogel adhesive to prevent ohmicimpedance reduction resulting in reduction of signal amplitude. This mayalso help prevent hydrocolloid adhesive degradation. In particular, asshown the non-limitative alternative exemplar in FIGS. 1I and 1J;several layers may be used. Herein, Layer 1 may be a hydrocolloid thatis an adhesive designed for long term skin contact by absorbing sweatand cells. Layer 2 may then also be a layer designed for long-term skincontact, however, this layer 2 isolates Layer 3 from contacting theskin. The smaller dimensions of Layer 2 create a gap between Layers 1and 3. When Layer 1 and 3 bond together, it forms a water-tight sealaround Layer 2. This layer, Layer 2, also isolates the Hydrocolloid fromthe Hydrogel Adhesive, protecting the adhesive properties of theHydrocolloid. Layers 3 and 5 would then generally be waterproof layersthat are electrically isolating, double-sided adhesives. These twolayers encapsulate the hydrogel adhesive, preventing a “short circuit”described relative to layer 4 below. Layer 4 is the hydrogel adhesivethat is the conductive element hereof. The three islands of hydrogeladhesive of Layer 4 must be kept electrically isolated from each other.However as the hydrocolloid in layer 1 absorbs sweat, it too becomesconductive and creates a potential “short circuit” between the threeislands of hydrogel adhesive in Layer 4, reducing signal amplitude.Nevertheless, this “short circuit” may be prevented by layers 3 and 5,described above.

Some alternative implementations hereof may include a driven right legECG circuit with one or more chest only electrodes (“Driven ChestElectrode”). In addition to the electrodes used to measure a single ormultiple lead electrocardiogram signal, a device 100 may use anadditional electrode, as for example the reference electrode 110 (seeFIGS. 1A, 1C, 1D and 1G, e.g.) to reduce common mode noise. Such anelectrode may function in a manner similar to the commonly-used drivenright leg electrode, but may here be located on the patient's chestrather than on the patient's right leg but nevertheless thisthird/reference electrode may play the role of the leg electrode. Thischest electrode may thus mimic a right leg electrode and/or beconsidered a proxy driven right leg electrode. A circuit, or portion ofan overall circuit, adapted to operate in this fashion may include anumber of amplifier stages to provide gain, as well as filtering toensure circuit stability and to shape the overall frequency response.Such a circuit may be biased to control the common mode bias of theelectrocardiogram signal. This driven chest electrode implementation maybe used in conjunction with a differential or instrumentation amplifierto reduce common mode noise. In this case, the sense electrode may beused as one of the electrocardiogram electrodes. Alternatively, asingle-ended electrocardiogram amplifier may be used where thedifferential electrocardiogram signal is referenced to ground or to someother known voltage.

A circuit or sub-circuit 200 using a transistor 201 as shown in FIG. 2may be such a circuit (aka module) and may thus include as further shownin FIG. 2A, a sense electrode 202, a drive electrode 203, and anamplifier 204. Both the sense and drive electrodes 202, 203 are placedon the patient's chest such that they provide an electrical connectionto the patient. The amplifier 204 may include gain and filtering. Theamplifier output is connected to the drive electrode, the invertinginput to the sense electrode, and the non-inverting input to a biasvoltage 205. The amplifier maintains the voltage of the sense electrodeat a level close to the bias voltage. An electrocardiogram signal maythen be measured using additional electrodes. Indeed, as was the casefor the improved conductivity through use of anisotropic adhesiveportions above, here also or alternatively, the use of this thirdelectrode as a proxy for a right leg electrode (i.e., proxy driven rightleg electrode) can provide signal reception otherwise unavailable. Cleansignals may thus allow for receiving cardiac P waves which enhances thepossibility to detect arrhythmias that couldn't otherwise be detected.

Further alternative descriptions of circuitry include that which isshown in FIGS. 2B and 2C; in which are shown non-limiting alternativesin which three adjacent electrodes E1, E2, and E3 may be used to pick upthe ECG signal, one of which electrodes playing the role of the distantlimb electrode of traditional ECG monitors. Because theelectrode-patient interface has an associated impedance (Re1 and Re2),current flowing through this interface will cause a difference involtage between the patient and the electrode. The circuit may use asense electrode (E1) to detect the patient voltage. Because thisexemplar circuit node has a high impedance to circuit ground (GND), verylittle current flows through the electrode interface, so that thevoltage drop between the patient and this node is minimized. The firstof these alternative, non-limiting circuits (FIG. 2B) also contains anamplifier (U1) whose low-impedance output is connected to a separatedrive electrode (E2). The amplifier uses negative feedback to controlthe drive electrode such that the patient voltage (as measured by thesense electrode E1) is equal to the bias voltage (V1). This mayeffectively maintain the patient voltage equal to the bias voltagedespite any voltage difference between the driven electrode (E2) and thepatient. This can include voltage differences caused by powerline-induced current flowing between the drive electrode and the patient(through Re2). This arrangement differs from a traditional‘driven-right-leg’ circuit in at least two ways: the driven electrode isplaced on the patient's chest (rather than the right leg), and the ECGsignal is a single-ended (not differential) measurement taken from athird electrode (E3). Because all electrodes are located on thepatient's chest in a chest-mounted example, a small device placed theremay contain all the necessary electrodes for ECG measurement. Onepossible benefit of the single-ended measurement is that gain andfiltering circuitry (U2 and associated components (FIG. 2C)) necessaryto condition the ECG signal prior to recording (ECG Output) requiresfewer components and may be less sensitive to component tolerancematching. The examples of FIGS. 2A, 2B and 2C are non-limiting examplesand not intended to limit the scope of the claims hereto as othercircuits with other circuit elements can be formed by skilled artisansin view hereof and yet remain within the spirit and scope of claimshereof.

In many implementations, a system hereof may include other circuitryoperative together with the ECG electrodes, which may thus beaccompanied by other sensors to provide time concordant traces of: i)ECG p-, qrs-, and t-waves; ii) O2 Saturation, as measured by PulseOxymetry; and/or iii) xyz acceleration, to provide an index of physicalactivity. Such circuitry may be implemented to one or more of thefollowing electrical specifications. The overall system might in someimplementations include as much as two weeks (or more) of continuous runtime; gathering data during such time. Some implementations may beadapted to provide as many or even greater than 1000 uses. Alternativesmay include operability even after or during exposure to fluids orwetness; in some such examples being water resistant, or waterproof, orwatertight, in some cases continuing to be fully operable when fullysubmerged (in low saline water). Other implementations may include fastdata transfer, as for an example where using an HS USB for full datatransfer in less than about 90 seconds. A rechargeable battery maytypically be used.

A further alternative implementation may include an electronic “ground”:In a device hereof, mounted entirely on a flexible circuit board, theground plane function may be provided by coaxial ground leads adjacentto the signal leads. The main contribution of this type of groundingsystem may be that it may allow the device the flexibility required toconform and adhere to the skin.

For electrocardiograph; EKG or ECG, some implementations may includegreater than about 10 Meg Ohms input impedance; some implementations mayoperate with a 0.1-48 Hz bandwidth; and some with an approximate 256 HzSampling Rate; and may be implementing 12 Bit Resolution. For PPG andPulse Oximeter, operation may be with 660 and 940 nm Wavelength; about80-100 SpO2 Range; a 0.05-4.8 Hz Bandwidth; a 16 Hz Sampling Rate; and12 bit resolution. For an accelerometer: a 3-Axis Measurement may beemployed, and in some implementations using a±2 G Range; with a 16 HzSampling Rate; and a 12 Bit Resolution.

For pulse oximetry, an option for PPG ambient light subtraction may beincluded. A method and circuitry for reducing errors in pulse oximetrycaused by ambient light is described and a circuitry option shown inFIG. 2D. Here a correlated double sampling technique is shown for use toremove the effect of ambient light, photo-detector dark current, andflicker noise.

The schematic shown in FIG. 2D may be used where, first, the noisesignal may be measured. The light sources are turned off, switch S1 isclosed, and switch S2 is open. This allows charge proportional to thenoise signal to accumulate on C1. Then switch S1 is opened. At thispoint the voltage on C1 is equal to the noise signal voltage. Next, thelight signal may be measured. The light source is turned on, switch S2is closed, and charge is allowed to flow through C1 and C2 in series.Then, S2 is opened, and the voltage is held on C2 until the nextmeasurement cycle when the whole process is repeated.

If C1 is much larger than C2, nearly all the voltage will appear on C2,and the voltage on C2 will be equal to the noise-free signal (s).Otherwise, the voltage on C2 will be a linear combination of theprevious C2 voltage (p) and the noise-free signal: (C2*s+C1*p)/(C1+C2).This has the effect of applying a first-order, low-pass, IIRdiscrete-time filter to the signal. If this filtering effect is notdesired, the voltage on C2 may be discharged to zero before the signalis measured each cycle, so that the signal held on C2 is simply:(C2*s)/(C1+C2).

This circuit may be used with a trans-impedance amplifier in place ofresistor R, a phototransistor in place of the photodiode, and FETs inplace of the switches. The output may be followed by additionalbuffering, amplification, filtering and processing stages.

Some summary methodologies may now be understood with relation to FIG.3, though others may be understood through and as parts of the remainderof the disclosure hereof. A flow chart 300 as in FIG. 3 may demonstratesome of the alternatives; where an initial maneuver 301 might be theapplication of the device 100 to the patient. Indeed, this might includesome one or more of the alternatives for adhesive application asdescribed here above, whether by/through use of an adhesive such as that113 of FIG. 1D, or that of FIGS. 1E, 1F and/or 1G. Then, as shown, inmoving by flow line 311, a data collection operation 302 may beimplemented. Note, this might include a continuous or substantiallycontinuous collection or an interval or periodic collection or perhapseven a one-time event collection. This may depend upon the type of datato be collected and/or be dependent upon other features or alternatives,as for example whether a long term quantity of data is desired, for ECGfor example, or whether for example a relative single data point mightbe useful, as in some cases of pulse oximetry (sometimes a singlesaturation point might be of interest, as for example, if clearly toolow, though comparison data showing trending over time, may indeed bemore typical).

Several alternatives then present in FIG. 3, flow chart 300; a firstsuch might be the following of flowline 312 to the transmission of dataoperation 303, which could then involve either wireless or wired (e.g.,USB or other) data communication from the device 100 to data analysisand/or storage devices and/or systems (not separately shown in FIG. 3;could include computing devices, see e.g., FIG. 4 described below, orthe like). Options from this point also appear; however, a first suchmight include following flow line 313 to the data analysis operation 304for analyzing the data for determination of the relative health and/orfor condition diagnosis of a patient. Computing systems, e.g., acomputer (could be of many types, whether hand-held, personal ormainframe or other; see FIG. 4 and description below) could be used forthis analysis; however, it could be that sufficient intelligence mightbe incorporated within the electronics 103 of device 100 such that someanalysis might be operable on or within device 100 itself. Anon-limiting example, might be a threshold comparison, as for examplerelative to pulse oximetry where when a low (or in some examples,perhaps a high) threshold level is reached an indicator or alarm mightbe activated all on/by the electronics 103 of the device 100.

A similar such example, might be considered by the optional alternativeflow path 312 a which itself branches into parts 312 b and 312 c.Following flow path 312 a, and then, in a first example path 312 b, askip of the transmit data operation 303 can be understood wherebyanalysis 304 might be achieved without substantial data transfer. Thiscould explain on board analysis, whether as for example according to thethreshold example above, or might in some instances include moredetailed analysis depending upon how much intelligence is incorporatedon/in the electronics 103. Another view is relative to how muchtransmission may be involved even if the transmission operation 303 isused; inasmuch as this could include at one level the transmission ofdata from the patient skin through the conductors 108, 109 and/or 110through the traces 107 to the electronics 103 for analysis there. Inother examples, of course, the transmission may include off-boarddownloading to other computing resources (e.g., FIG. 4). In some cases,such off-loading of the data may allow or provide for more sophisticatedanalysis using higher computing power resources.

Further alternatives primarily may involve data storage, both when andwhere, if used. As with intelligence, it may be that either some or nostorage or memory may be made available in/by the electronics 103on-board device 100. If some storage, whether a little or a lot, is madeavailable on device 100, then, flow path 312 a to and through path 312 cmay be used to achieve some storing of data 305. This may in many casesthen, though not necessarily be before transmission or analysis (note,for some types of data multiple paths may be taken simultaneously, inparallel though perhaps not at the same time or serially (e.g., paths312 b and 312 c need not be taken totally to the exclusion of theother), so that storage and transmission or storage and analysis mayoccur without necessarily requiring a completion of any particularoperation before beginning or otherwise implementing another). Thus,after (or during) storage 305, flow path 315 a may be followed forstored data which may then be transmitted, by path 315 b to operation303, and/or analyzed, by path 315 c to operation 304. In such a storageexample, which in many cases may also be an on-board storage example,data can be collected then stored in local memory and lateroff-loaded/transmitted to one or more robust computing resources (e.g.,FIG. 4) for analysis. Frequently, this can include long term datacollection, e.g., in the manner of days or weeks or even longer, and maythus include remote collection when a patient is away from a doctor'soffice or other medical facilities. Thus, data can be collected from thepatient in the patient's real world circumstances. Then, aftercollection, the data can be transmitted from its storage on device 100back to the desired computing resource (FIG. 4, e.g.), and suchtransmission might be wireless or wired or come combination of both, asfor example a blue tooth or Wi-Fi connection to a personal computer(FIG. 4 for one example) which might then communicate the data over theinternet to the designated computer for final analysis. Another examplemight include a USB connection to a computer, either to a PC or amainframe (FIG. 4), and may be to the patient computer or to the doctorcomputer for analysis.

If little or no storage or memory is resident on device 100 (or in someexamples even where there may be a large amount of resident memoryavailable), then, relatively soon after collection, the data would needto or otherwise might desirably either or both be transmitted and thenstored, see path 313 a after operation 303, and/or transmitted andanalyzed, paths 312 and 313. If path 313 a is used, then, moretypically, the data storage may be in/on computing resources (not shownin FIG. 3, but see FIG. 4 described below) off-board (though on-boardmemory could be used as well), and then, any of paths 315 a, 315 b and315 c may be used.

A feature hereof may include an overall system including one or moredevices 100 and computing resources (see FIG. 4, for example) whetheron-board device(s) 100, or separate, as for example in personal ormobile or hand-held computing devices (generally by FIG. 4), the overallsystem then providing the ability for the physician or doctor to haveimmediate, in-office analysis and presentation of collected test data.This would in some implementations allow for on-site data analysis fromthe device without utilization of a third party for data extraction andanalysis.

Alternative implementations hereof may thus include one or more hardwareand software combinations for multiple alternative data sourceinterpretations. As noted above, a device 100 hereof includes hardwarethat monitors one or more of various physiologic parameters, thengenerates and stores the associated data representative of the monitoredparameters. Then, a system which includes hardware such as device 100and/or the parts thereof, and software and computing resources (FIG. 4,generally) for the processing thereof. The system then includes not onlythe collection of data but also interpretation and correlation of thedata.

For example, an electrocardiogram trace that reveals a ventriculararrhythmia during intense exercise may be interpreted differently thanthe same arrhythmia during a period of rest. Blood oxygen saturationlevels that vary greatly with movement can indicate conditions that maybe more serious than when at rest, inter alia. Many more combinations ofthe four physiologic parameters are possible, and the ability ofsoftware hereof to display and highlight possible problems will greatlyaid the physician in diagnosis. Thus, a system as described hereof canprovide beneficial data interpretation.

Some of the features which can assist toward this end may be subsumedwithin one or more of operations 303 and 304 of FIG. 3, wherein datacollected on a device 100 can rather simply be communicated/transmittedto computing resources (again, whether on-board device 100 or discretetherefrom as e.g., FIG. 4). For an example, when a patient having had adevice applied (operation 301) may return to a physician's office aftera test period wherein data was collected (operation 302) the device isconnected via one or more data transmission alternatives, as forexample, USB to a computer (Windows or Mac) (generally with reference toFIG. 4 and description thereof) in the office, allowing immediateanalysis by the physician while the patient waits (note, the device 100may first have been removed from the patient or might remain thereonpending transmission and analysis for determination of whether more datamay be desired). In some implementations, data analysis time may berelatively quick, at approximately 15 minutes in some implementations,and might be achieved with a user-friendly GUI (Graphic User Interface)to guide the physician through the analysis software.

The analysis/software package may be disposed to present the physicianwith results in a variety of formats. In some implementations, anoverview of the test results may be presented, either together with orin lieu of more detailed results. In either case, a summary of detectedanomalies and/or patient-triggered events may be provided, either aspart of an overview and/or as part of the more detailed presentation.Selecting individual anomalies or patient-triggered events may providedesirable flexibility to allow a physician to view additional detail,including raw data from the ECG and/or from other sensors. The packagemay also allow data to be printed and saved with annotations inindustry-standard EHR formats.

In one implementation, patient data may be analyzed with software havingthe one or more of the following specifications. Some alternativecapabilities may include: 1. Data Acquisition; i.e., loading of datafiles from device; 2. Data Formatting; i.e., formatting raw data toindustry standard file formats (whether, e.g., aECG (xml); DICOM; orSCP-ECG) (note, such data formatting may be a part of Acquisition,Storage or Analysis, or may have translation from one to another (e.g.,data might be better stored in a compact format that may needtranslation or other un-packing to analyze)); 3. Data Storage (whetherlocal, at a clinic/medical facility level or e.g., in the Cloud(optional and allows offline portable browser basedpresentation/analysis); 4. Analysis which inter alia, may include, e.g.,noise filtering (High pass/Low pass digital filtering); and/or QRS(Beat) detection (in some cases, may include Continuous Wave Transform(CWT) for speed and accuracy); and/or 5. Data/Results Presentation,whether including one or more graphical user interface(s) (GUIs) perhapsmore particularly with an overall Summary and/or General Statisticsand/or Anomaly Summary of Patient triggered event(s); presentation ofadditional levels of detail whether of Strip view(s) of anomaly data byincident (previous, next) Blood Oxygen saturation, stress correlation orthe like; and/or allowing care provider bookmarking/annotations/notes byincident and/or Print capability.

Further, on alternative combinations of hardware with proprietarysoftware packages: I) One on-device software package may be adapted tostore the measurements from the data signals acquired from one or moreof EKG/ECG (whether right leg and/or p-, qrs- and/or t-waves), or O2saturation, or xyz acceleration, in a time concordant manner, so that aphysician may access a temporal history of the measurements (say, insome examples, over a 1-2 week interval), which would provide usefulinformation on what the patient's activity level was prior to, during,and after the occurrence of a cardiac event. ii) an alternative toalternately manage the real-time transmission of the real-time measuredparameters to a nearby station or relay. And/or; iii) an off-device ECGanalysis software aimed at recognizing arrhythmias.

The software mentioned above may be industry understood softwareprovided by a 3rd party, or specially adapted for the data developed andtransmitted by and/or received from a wearable device 100 hereof.Thorough testing using standard (MIT-BIH/AHA/NST) arrhythmia databases,FDA 510(k) approvals preferred. Such software may be adapted to allowone or more of automated ECG analysis and interpretation by providingcallable functions for ECG signal processing, QRS detection andmeasurement, QRS feature extraction, classification of normal andventricular ectopic beats, heart rate measurement, measurement of PR andQT intervals, and rhythm interpretation.

In many implementations, the software may be adapted to provide and/ormay be made capable of supplying one or more of the followingmeasurements:

TABLE 1 1. Heart Rate Min, Max and Average 2. QRS duration average 3. PRinterval average 4. QT interval average 5. ST deviation averageand, may be adapted to recognize a broad range of arrhythmias such asthose set forth here:

TABLE 2A 1. SINUS RHYTHM 2. SINUS RHYTHM + IVCD 3. SINUS BRADYCARDIA 4.SINUS BRADYCARDIA + IVCD 5. SINUS TACHYCARDIA 6. PAUSE 7. UNCLASSIFIEDRHYTHM 8. ARTIFACT

This first group of 8 given above are arrhythmia types that may berecognizable even if there is no discernible P wave. They are the onestypically recognized by existing products in the outpatient monitoringmarket that we propose to address.

A second set or group of arrhythmias; below, may require a discernibleand measurable P wave. Some implementations hereof may be adapted to beable to detect and recognize them, as device 100 may be able asdescribed above to detect P waves, depending of course, and for example,on whether the strength of the P wave which may be affected by device100 placement or patient physiology.

TABLE 2B  9. ATRIAL FIBRILLATION/FLUTTER SVR (slow) 10. ATRIALFIBRILLATION/FLUTTER CVR (normal rate) 11. ATRIAL FIBRILLATION/FLUTTERRVR (rapid 12. FIRST DEGREE AV BLOCK + SINUS RHYTHM 13. FIRST DEGREE AVBLOCK + SINUS TACHYCARDIA 14. FIRST DEGREE AV BLOCK + SINUS BRADYCARDIA15. SECOND DEGREE AV BLOCK 16. THIRD DEGREE AV BLOCK 17. PREMATUREATRIAL CONTRACTION 18. SUPRAVENTRICULAR TACHYCARDIA 19. PREMATUREVENTRICULAR CONTRACTION 20. VENTRICULAR COUPLET 21. VENTRICULAR BIGEMINY22. VENTRICULAR TRIGEMINY 23. IDIOVENTRICULAR RHYTHM 24. VENTRICULARTACHYCARDIA 25. SLOW VENTRICULAR TACHYCARDIA

Further in alternative software implementations; some sample screenshotsare shown in FIG. 5. A first such alternative is shown in FIG. 5A, whichis an example screenshot showing ECG and Oxygen Saturation data taken byusing a patch device such as a device 100 hereof. An extremely cleansignal is shown (no filtering or smoothing has been done on this data).Distinct p-waves are also shown (3 of which are shown as an example witharrows). P wave detection can be extremely important for ECG anomalydetection. Oxygen Saturation, as measured by Pulse Oxymetry, is shown onthe bottom plot. This is data taken by a device on the chest, and istaken in time concordance with the ECG data.

Another alternative is shown in FIG. 5B, which is an example screenshotof Analysis Software. This is a sample of ECG data taken from theMIT-BIH Arrhythmia Database, Record 205. As analyzed by the Analysissystem hereof, we see in the Event Occurrences Summary list (top, left)five (5) anomaly types (plus normal sinus rhythm). This list also showsthe number of occurrences of each anomaly, total duration of the anomalyin the complete ECG, and the percent time this anomaly occurs in thecomplete ECG. To view specific instances of each anomaly, the userdouble clicks the specific row in the Event Occurrences Summary list, asshown in FIG. 5C.

As introduced, FIG. 5C is an example screenshot showing specificinstance of Ventricular Tachycardia. The ECG plot automaticallynavigates to the specific time in the ECG waveform, and marks thebeginning and end of the event. More detailed data about this specificevent is now shown in the Occurrence Details: HR Average, HR Max, etc.for the duration of this event. To show the instances of another anomalyin this ECT, the user can click on the Premature Ventricular Contraction(PVC) row of the Event Occurrences Summary, as shown FIG. 5D.

As introduced, FIG. 5D is an example screenshot showing specificinstance of Premature Ventricular Contraction. This shows occurrences ofthe PVC. The Start Times list (middle top) shows all instances of PVCoccurrences in this ECG, and lists the start time for each occurrence.In this case, the user can click on the PVC that starts at 00:15:27 (the11^(th) occurrence). The ECG plot is automatically taken to this pointin time to show and indicate the PVC instances in the waveform. Sincethere are 3 instances of a PVC in this timeslot, all 3 occurrences aremarked.

As mentioned above, in one aspect of the developments hereof, ECGsignals collected in time concordance with pulse oximetry signals may beused to reduce the noise in the pulse oximetry signals and to permit thecalculation of values for oxygen saturation, particularly incircumstances where sensors pulse oximetry data are placed onnoise-prone locations of a patient, such as the chest. In someembodiments, this aspect may be implemented by the following steps: (a)measuring an electrocardiogram signal over multiple heart beats; (b)measuring one or more pulse oximetry signals over multiple heart beatssuch that the electrocardiogram signal and the one or more pulseoximetry signals are in time concordance over one or more heart beats;(c) comparing a portion of the electrocardiogram signal and the one ormore pulse oximetry signals in time concordance over one or more heartbeats to determine a constant component and a primary periodic componentof each of the one or more pulse oximetry signals; and (d) determiningoxygen saturation from the constant components and primary periodiccomponents of the one or more pulse oximetry signals. Measurement of theECG signals and pulse oximetry signals may be implemented by embodimentsof devices hereof. In particular, pulse oximetry signals may be areflective infrared signal and a reflective red light signal collectedby a photodetector in a device hereof. Intervals of pulse oximetrysignals corresponding to heart beats may be determined by comparing suchsignals to the time concordant ECG signals. For example (not intended tobe limiting), successive R-wave peaks of a time concordant ECG signalmay be used to identify such intervals, although other features of theECG signal may be used as well. Once such intervals are identified,values at corresponding times within the intervals may be averaged toreduce signal noise and to obtain more reliable values for the constantcomponents (sometimes referred to as the “DC components”) and the mainperiodic components (sometimes referred to as the “AC components”) ofthe pulse oximetry signals, e.g. Warner et al, Anesthesiology, 108:950-958 (2008). The number of signal values recorded in an intervaldepends on the signal sampling rate of the detectors and processingelectronics employed. Also, as the intervals may vary in duration, theaveraging may be applied to a subset of values in the intervals. Asdescribed below, oxygen saturation values may be computed from such DCand AC components using conventional algorithms. The number of heartbeats or intervals over which such averages may be computed may varywidely, as noted below. In some embodiments, signals from one or moreheart beats or intervals may be analyzed; in other embodiments, signalsfrom a plurality of heart beats or intervals may be analyzed; and insome embodiments, such plurality may be in the range of from 2 to 25, orin the range of from 5 to 20, or in the range of from 10 to 20.

In further alternative implementations, a linear regression algorithmfor Oxygen Saturation may be used. As such, the patient's ECG signal maybe used to determine when heart beats occur. The beat locations allowcorrelated time averaging of each of the two photoplethysmogram signals.A linear regression of the ensemble averages may then be used todetermine the linear gain factor between the two signals. This gainfactor can be used to determine the patient oxygen saturation.

ECG data may be recorded in time-concordance with two or morephotoplethysmographs of different light wavelengths. The heart beats aredetected in the ECG signal. These heart beats allow for definition of a‘frame’ of photoplethysmogram data for the time between two adjacentheart beats. Two or more of these frames can then be averaged togetherat each point in time to create an average frame for the time interval.Because the photoplethysmogram is correlated with the heartbeat, thephotoplethysmograph signal is reinforced by this averaging. However, anymotion artifact or other noise source that is uncorrelated in time withthe heartbeat is diminished. Thus, the signal-to-noise ratio of theaverage frame is typically higher than that of the individual frames.

Having constructed an average frame for at least twophotoplethysmographs of different light wavelengths, linear regressioncan then be used to estimate the gain between the two average framesignals. This gain value may be used to estimate blood oxygen saturationinformation or other components present in the blood such as hemoglobin,carbon dioxide or others. The process may be repeated for additionallight wavelengths in order to do so.

An exemplar/alternative method hereof may include determining the gainbetween particular signals, as between the red and IR frame signals,if/when such may be used. These may be found by averaging the two framestogether first. This may result in a signal with reduced noise. The gainis found by performing linear regression of the red versus combined andIR versus combined and then finding the ratio of these two results.

Another method involves selecting a possible gain value, multiplying theaverage frame signal by it, and determining the residual error withrespect to an average frame of a different wavelength. This process maybe repeated for a number of potential gain values. While simple linearregression finds the global minimum gain value, this method allows forfinding local minima. Thus, if it is likely that the global minimumrepresents correlation caused by motion artifact, venous blood movementor another noise source, it may be ignored, and a local minimum may beselected instead.

As mentioned above, patient wearable devices hereof for implementing theabove aspects may be particularly useful for monitoring oxygensaturation in noisy regions for such measurements, for example, wherethere is significant local skin movement, such as the chest location.

One embodiment of the above aspect hereof is illustrated in FIGS. 6A-6C.In FIG. 6A, curve A (600) illustrates time varying output of thephotodiode of a device hereof for infrared (IR) reflection and curve B(602) illustrates time varying output of the photodiode of the devicefor red light reflection. In some embodiments, the skin is alternativelyilluminated by the red and IR LEDs to generate the signals collected bythe same photodiode. In FIG. 6B, time synchronized (i.e. timeconcordant) ECG data, illustrated by curve C (604), is added to the plotof FIG. 6A. Peak values in the ECG data (e.g. peaks 606 and 608) may beused to define frames or intervals of pulse oximetry data. Additionalconsecutive frames or intervals are indicated by 612 and 614, andfurther frames may be similarly determined. In accordance with thisaspect, pulse oximetry data from a plurality of frames is collected. Themagnitude of the plurality may vary widely depending on particularapplications. In some embodiments, the plurality of frames collected isfrom 5 to 25; in one embodiment, a plurality is between 8 and 10 frames.Typically, frames or intervals of pulse oximetry data contain differentnumbers of signal samples. That is, output from the sensors may besampled at a predetermined rate, such a 32 samples per second. If thetime between ECG peaks varies, then the number of samples per frame willvary. In one embodiment, features in the ECG data serving as thestarting points of a frame are selected so that an associated peak inthe pulse oximetry data is approximately in the mid-point, or center, ofthe frame, after which a predetermined number of signal samples arerecorded for each frame. Preferably in this embodiment, thepredetermined number is selected to be large enough to ensure that thepulse oximetry signal peak is roughly mid-frame. Sample valuescorresponding to time points above the predetermined value are not used.After a plurality of frames of data is collected, averages of the valuesat corresponding time points of the frames are computed. The values fromsuch averages AC and DC components of the pulse oximetry data aredetermined and are then used to compute relative oxygen saturation byconventional methods, such as the ratio-of-ratios algorithm, e.g.Cypress Semiconductor document No. 001-26779 Rev A (Jan. 18, 2010). Thisbasic procedure is summarized in the flow chart of FIG. 6C. Frame size(in terms of number of samples) is determined (620). Values of samplesat corresponding time points within each frame are summed (622), afterwhich average values for each time point are computed which, in turn,give the AC and DC components of IR and red light reflection withreduced noise. In some embodiments, values for these components can beused to compute oxygen saturation using conventional algorithms (626).Relative values for oxygen saturation may be converted into absolutevalues by calibrating the measurements for particular embodiments.Calibration may be carried out in controlled environments whereindividuals are exposed to varying atmospheric concentrations of oxygenand measured oxygen saturation values are related to correspondingoxygen levels.

In addition to the above embodiment for comparing ECG signals with pulseoximetry signals, a range of other embodiments for such comparing iswithin the comprehension of those of ordinary skill in the art. Forexample, in order to find peaks of the AC component of pulse oximetrysignals in the presence of noise, features of the time concordant ECGsignal that are located at characteristic times preceding and succeedingthe pulse oximetry maximum and/or minimum values may be used to reliablydetermine the pulse oximetry peak and minimum values when averaged overa plurality of heart beats (without the need to average all values ofthe pulse oximetry signal over the heart beats). For example, if, withinan interval, the R wave peak of an ECG signal characteristicallypreceded a pulse oximetry signal maximum by x milliseconds and trailed apulse oximetry signal minimum by y milliseconds, then the essentialinformation about the AC component of the pulse oximetry signal may beobtained by repeated measurements of just two values of pulse oximetrysignals.

In some embodiments, values for IR or red reflection measured by thephotodiode may be used to estimate depth and/or rate of respiration. InFIG. 6D, a curve (630) of Red or IR values over time is illustrated. InFIG. 6E, maximum values and minimum values of curve (630) are shown bydashed curves (632) and (634), respectively. The difference between themaximum and minimum values at a time point is monotonically related tothe depth of breath in an individual being monitored. Thus, asillustrated, breaths at time (636) are shallower than those at time(638). In some embodiments, depth of breath versus time may be computedand monitored in an individual. Over time, the rate of respiration canbe evaluated from the curve of maximum and minimum values over time.

Moreover, moving from an appreciation of a derivation of a respirationwaveform from ECG R-S amplitude and/or R-R intervals, it has been foundthat a PPG and/or pulse oximeter as described herein can be used torelatively directly estimate a respiration waveform. As the chestexpands and contracts during breathing, the motion hereof shows up as awandering baseline artifact on the PPG signals. The respiration signalmay be isolated by filtering out the PPG data to focus on thebreathing/respiration signal. This may be particularly so with achest-mounted PPG.

In addition, a chest mounted accelerometer may also or alternatively beused to measure the respiration waveform, especially when the user islying on his/her back. As the chest expands and contracts, the chestaccelerates up and down (or transversely, or otherwise depending uponorientation), which can be measured by the accelerometer.

Either of these, PPG and/or accelerometer, devices and/or methods may beused discretely or in combination with each other and/or with theabove-described ECG-based respiration estimation technique. Usingmultiple methods may improve accuracy when compared to estimates basedon a single method. Respiration rate and depth may then be estimatedfrom the respiration signal using time-domain and/or frequency domainmethods.

In some implementations, heart beat timing (e.g., from ECG) and PPGsignals can be used to determine pulse transit time; i.e., the time forthe pressure wave to travel from the heart to other locations in thebody. Measurements of pulse transit time may then be used to determineor estimate blood pressure. Note, the heartbeat timing, ECG and/or PPGsignals may be generated by conventional or other to-be-developedmethods, systems or devices, or may be developed by wearable devicessuch as those otherwise described herein. I.e., the algorithms hereofmay be separately usable, as well as being usable in the wearablecardiac device.

As disclosed herein elsewhere, the PPG signals of several heart beatsmay be averaged by correlating each with a respective heartbeat. Theresult is a PPG frame where the heart rate-correlated PPG signal isreinforced while uncorrelated noise is diminished. Moreover, because thePPG frame is already correlated to the timing of the heartbeat, pulsetransit time may be estimated by determining the location of either thepeak or minimum with respect to either the beginning or end of the frameitself. This may be done either by finding the minimum and/or maximumsample(s), or by interpolating the signal to find points betweenmeasured samples. For example, interpolation may be done with aquadratic fit, a cubic spline, digital filtering, or many other methods.

The pulse transit time may also be estimated by correlating the PPGframe with a sample signal. By shifting the two signals with respect toeach other, the time shift resulting in the maximum correlation may bedetermined. If the sample signal is an approximation of the expected PPGframe, then the time shift with maximum correlation may be used todetermine the pulse transit time.

An exemplar methodology or algorithm herefor is described here and shownin the drawing FIGS. 7A, 7B and 7C. Initially, such a method 710 (whichincludes and/or is defined by parts 710 a, 710 b and/or 710 c) takes atleast one heartbeat (typical ECG) signal 712 and at least one PPG signal711 as input as shown in FIG. 7A, e.g. The heartbeat timinginformation/signal 712 is used to generate heartbeat timing informationby detecting the R-wave or other ECG feature from each beat; multipleECG signals (i.e. different leads from locations on the body) may beused to obtain a better estimate of the heartbeat timing information.The PPG 711 may use a single light wavelength or signals from multiplelight wavelengths. Using the corresponding heartbeat timing informationrelated to each PPG signal 711, each PPG signal 711 is segmented into“frames,” see PPG Frame 1, PPG Frame 2 and PPG Frame N in FIG. 7A, whereeach frame contains the PPG signal of a single wavelength for theduration of one corresponding beat of the heart.

Optionally, but, typically, a PPG signal quality estimate may also beperformed. An example of this is shown as method part 710 b in FIG. 7B.This estimate may consider the variance of the PPG signal, the estimatedsignal-to-noise ratio of the PPG signal, PPG signal saturation, patientmotion information from an accelerometer or gyroscope, an ECG orimpedance measurement noise estimate, or other information about the PPGsignal quality. Shown in FIG. 7B is an exemplar using accelerometersignal 713 in conjunction with PPG signal 711 to generate a PPG SignalQuality Value/Estimate 714. This signal quality estimate 714 may then beused in conjunction with the heartbeat timing information 712 togenerate the gain for each frame, see PPG Frame 1 Gain, PPG Frame 2 Gainand PPG Frame N Gain in FIG. 7B, where lower signal quality results in alower gain. To reduce computation time, the signal quality estimate 714may be omitted and a constant may be used for the gain information.

As shown in FIG. 7C, the gain information (PPG Frame 1 Gain, PPG Frame 2Gain and PPG Frame N Gain from FIG. 7B) may be used (here shown ascombined/manipulated) with the frame information (PPG Frame 1, PPG Frame2 and PPG Frame N from FIG. 7A) to create a weighted, n-samplemoving-average frame 715, where the PPG signal that is correlated withthe heartbeat timing is reinforced while the uncorrelated noise isreduced. The number of samples included in the frame (n) 715 may beadapted to reduce noise or decrease response time. The frames may beadditionally weighted by time in order to increase the contribution ofrecent or near-future frames with respect to frames that are furtheraway and potentially less-relevant. This additional weighting by timemay be implemented using an IIR or FIR filter.

Once the average frame 715 has been produced for a given instant intime, the pulse transit time 716 may be determined by finding the shiftin the frame signal with respect to the heartbeat. This may be donesimply by finding the sample index 717 where the signal is at a minimumor maximum and comparing it with the frame boundary (heartbeat timing)to determine the pulse transit time. For a more precise result, thesignal may be interpolated 718 using a spline or polynomial fit aroundthe minimum or maximum values, allowing the minimum or maximum to bedetermined with greater precision than the sample rate. Finally, theframe may be compared 719 to a reference frame template, where theaverage frame is shifted with respect to the template. The shift withthe highest correlation between the average frame and the templateindicates the transit time 716. This reference template may be apredetermined signal, or it may be allowed to adapt by using a long-termframe average with a known transit time.

Note, such methodologies may be used with PPG and heartbeat timinginformation obtained from a variety of sources, including but notlimited to conventional and/or to-be-developed technologies; or, may beobtained one or the other alone or together and/or together with qualitysignal (PPG variance, estimated PPG signal-to-noise ratio, PPG signalsaturation, patient motion accelerometer or gyroscope data, an ECG orimpedance measurement noise estimate, or other information about the PPGsignal quality) obtained from a wearable device and/or system asdescribed further hereinbelow.

Some further alternatives may include data transmission and/orinterpretation by local medical facilities, whether physician or doctoroffices or e.g., ICU/CCU (Intensive Care/Coronary Care Units).Accordingly, a device 100 hereof that will measure one or more of avariety of physiologic signals, possibly including electrocardiogram,photoplethysmogram, pulse oximetry and/or patient acceleration signalswill be placed on the patient's chest and held with an adhesive asdescribed herein. The device transmits the physiologic signalswirelessly or by wire (e.g., USB) to a nearby base station forinterpretation and further transmission, if desired. The wirelesstransmission may use Bluetooth, Wi-Fi, Infrared, RFID (Radio FrequencyIDentification) or another wireless protocol. The device may be poweredby wireless induction, battery, or a combination of the two. The device100 monitors physiological signals and/or collects data representativethereof. The collected data may then be transmitted wirelessly or bywire connection, in real time, to the nearby base station. The devicemay be wirelessly powered by the base station or by battery, removingthe need for wires between the patient and the station.

Relatedly and/or alternatively, patients or wearers may be monitoredwirelessly in a hospital, including an ICU (Intensive Care Unit) orother facility. As such, an ECG signal may be measured on a patientusing a small, wireless patch device hereof. The signal is thendigitized and transmitted wirelessly to a receiver. The receiverconverts the signal back to analog, such that it approximates theoriginal ECG signal in amplitude. This output is then presented to anexisting hospital ECG monitor through the standard electrode leads. Thisallows the patient to be monitored using existing hospitalinfrastructure without any lead wires necessarily connecting the patientto the monitor. Patient chest impedance may be measured as well,allowing the reconstructed signal to approximate the ECG signal not onlyin amplitude, but in output impedance as well. This can be used todetect a disconnected patch. The output impedance may be continuouslyvariable, or it may have discrete values that may be selected (e.g. onelow value for a connected device and one high value to signify the patchhas come loose). The impedance may also be used to signify problems withthe wireless transmission.

Other alternative implementations may include coupling one or multiplesensors mounted to the forehead of an infant. Initially, a method ofobtaining oxygen saturation data by mounting a device in the forehead ofan infant might be used as introduced. However, an expansion oralternative may include coupling oxygen saturation sensors with relativeposition and temperature sensors on the same forehead-mounted device.The combined data can be utilized to ascertain if an infant is in anydanger of suffocation due to a face-down position.

Thus, some of the alternative combinations hereof may include one ormore of: 1) medical grade adhesives (from many possible sources)selected for their ability to maintain in intimate contact with the skinwithout damaging it, for several days (up to, say 10 days or two weeksin some examples), as well as operability with different types ofsensors; 2) conductive electrodes or photo-sensitive detectors able tosupply electrical signals from the skin or from the photo-response ofcutaneous or subcutaneous tissues to photo-excitation; 3) amplifiers,microprocessors and memories, capable of treating these signals andstoring them; 4) power supply for the electronics hereof with stored orwith wirelessly accessible re-chargeability; 5) flex circuits capable oftying the above elements together within a flexible strip capable ofconforming to a cutaneous region of interest.

Examples of physiological parameters that may be subject to monitoring,recordation/collection and/or analyzing may include one or more of:electrocardiograms, photo responses of photo-excited tissues for e.g.,oxygen saturation of blood; pulse rates and associated fluctuations;indications of physical activity/acceleration. One or more of these maybe used in monitoring ambulatory cardiac outpatients over several daysand nights, which could thereby provide for recording, for post-testanalysis, several days' worth of continuous ECG signals together withsimultaneous recording of O2 saturation and an index of physicalexertion. Similarly, one or more of these may be used in monitoringambulatory pulmonary outpatients over several days and nights forrecording, for post-test analysis, O2 saturation together withsimultaneous recording of an index of physical activity. Alternativelyand/or additionally, one or more of these could be used for monitoringin-patients or other patients of interest, as for example neonates,wirelessly (or in some cases wired), whether in clinics, emergencyrooms, or ICUs, in some instances detecting the parameters of EKG, O2and/or physical exertion, but instead of storing them would transmitthem wirelessly to either a bedside monitor or a central stationmonitor, thus freeing the patient from attachment to physical wires. Inparticular, devices hereof may be adhered to the forehead of a neonatefor monitoring respiration and oxygen saturation. In furtheralternatives, devices hereof may be used to monitor respiration and ECGof patients suffering from sleep apnea.

An exemplary computer system or computing resources which may be usedherewith will now be described, though it should be noted that manyalternatives in computing systems and resources may be available andoperable within the reasonably foreseeable scope hereof so that thefollowing is intended in no way to be limiting of the myriad possiblecomputational alternatives properly intended within both the spirit andscope hereof.

Some of the implementations of the present developments include varioussteps. A variety of these steps may be performed by hardware componentsor may be embodied in machine-executable instructions, which may be usedto cause a general-purpose or special-purpose processor programmed withthe instructions to perform the steps. Alternatively, the steps may beperformed by a combination of hardware, software, and/or firmware. Assuch, FIG. 4 is an example of computing resources or a computer system400 with which implementations hereof may be utilized. According to thepresent example, a sample such computer system 400 may include a bus401, at least one processor 402, at least one communication port 403, amain memory 404, a removable storage media 405, a read only memory 406,and a mass storage 407. More or fewer of these elements may be used in aparticular implementation hereof.

Processor(s) 402 can be any known processor, such as, but not limitedto, an Intel® Itanium® or Itanium 2® processor(s), or AMD® Opteron® orAthlon MP® processor(s), or Motorola® lines of processors. Communicationport(s) 403 can be any of an RS-232 port for use with a modem baseddialup connection, a 10/100 Ethernet port, a Universal Serial Bus (USB)port, or a Gigabit port using copper or fiber. Communication port(s) 403may be chosen depending on a network such a Local Area Network (LAN),Wide Area Network (WAN), or any network to which the computer system 400connects or may be adapted to connect.

Main memory 404 can be Random Access Memory (RAM), or any other dynamicstorage device(s) commonly known in the art. Read only memory 406 can beany static storage device(s) such as Programmable Read Only Memory(PROM) chips for storing static information such as instructions forprocessor 402.

Mass storage 407 can be used to store information and instructions. Forexample, hard disks such as the Adaptec® family of SCSI drives, anoptical disc, an array of disks such as RAID, such as the Adaptec familyof RAID drives, or any other mass storage devices may be used.

Bus 401 communicatively couples processor(s) 402 with the other memory,storage and communication blocks. Bus 401 can be a PCI/PCI-X or SCSIbased system bus depending on the storage devices used.

Removable storage media 405 can be any kind of external hard-drives,floppy drives, IOMEGA® Zip Drives, Compact Disc—Read Only Memory(CD-ROM), Compact Disc—Re-Writable (CD-RW), Digital Video Dis—Read OnlyMemory (DVD-ROM).

The components described above are meant to exemplify some types ofpossibilities. In no way should the aforementioned examples limit thescope of the invention, as they are only exemplary embodiments.

Embodiments of the present invention relate to devices, systems,methods, media, and arrangements for monitoring and processing cardiacparameters and data, inter alia. While detailed descriptions of one ormore embodiments of the invention have been given above, variousalternatives, modifications, and equivalents will be apparent to thoseskilled in the art without varying from the spirit of the invention.Therefore, the above description should not be taken as limiting thescope of the invention, which is defined by the appended claims.

What is claimed is:
 1. A method for determining pulse transit time in anindividual, the method comprising: providing one or more ECG sensors tosense an ECG signals, and providing one or more PPG sensors to sensefirst and second PPG signals of first and second light wavelengths, allof the one or more ECG sensors and the one or more PPG sensors areconfigured to be disposed on a single health monitoring deviceconfigured to be disposed on a portion of a body; sensing an ECG signal,the ECG signal including heartbeat information including informationfrom one or more heartbeats; and sensing the first and second PPGsignals corresponding to the first and second light wavelengths;generating two or more PPG frames of the first and second PPG signals,the two or more PPG frames each being defined by the one or moreheartbeats as included within the heartbeat information from the ECGsignal and the first and second PPG signals, each of the two or more PPGframes including the first and second PPG signals occurring in aninterval defined by the one or more heartbeats, the first and second PPGsignals thereby being correlated with the one or more heartbeats;creating two or more time concordance average frames from the two ormore PPG frames; the two or more time-concordance average framesincluding a first time-concordance average frame corresponding to afirst light wavelength selected from the first and second lightwavelengths and a second time-concordance average frame corresponding toa second light wavelength selected from the first and second lightwavelengths; the two or more time-concordance average frames beingcreated by: (a) measuring an ECG signal over the one or more heartbeats;(b) measuring the first and second PPG signals over the one or moreheartbeats such that the ECG signal and the first and second PPG signalsare in time concordance over the one or more heartbeats; (c) comparing aportion of the ECG signal and the first and second PPG signals in timeconcordance over the one or more heartbeats to determine a constantcomponent value and a primary periodic component value of each of thefirst and second PPG signals; the portion of the ECG signal defining aninterval within the one or more heartbeats corresponding with the PPGframes, the constant component and primary periodic component values atconcordant times within intervals averaged to calculate and define thefirst and second time-concordance average frames, the first and secondtime-concordance average frames reducing signal noise; and (d)determining oxygen saturation from constant component values and primaryperiodic component values of the first and second PPG signals; and,calculating a pulse transit time from the two or more time concordanceaverage frames, and by finding a shift in at least one of the first andsecond PPG signals in the one or more PPG frames with respect to the oneor more heartbeats using the two or more time concordance averageframes.
 2. A method according to claim 1 further comprising: calculatingblood pressure from the pulse transit time.
 3. A method according toclaim 1 comprising generating via the ECG signal by detecting an R-waveor other ECG feature from the one or more heartbeats of an individual.4. A method according to claim 1 comprising performing a PPG signalquality estimate.
 5. A method according to claim 4 the element ofperforming a PPG signal quality estimate further comprisingincorporating one or more of a PPG variance, an estimated PPGsignal-to-noise ratio, a PPG signal saturation, a patient motionaccelerometer or gyroscope data, an ECG or impedance measurement noiseestimate.
 6. A method according to claim 4 further comprising:generating a gain for a frame of the two or more PPG frames from the PPGsignal quality estimate in conjunction with the heartbeat information.7. A method according to claim 6, the generating a gain includes findinga second gain that has a lower gain value than the gain generatedaccording to claim 6; the finding the second gain comprising finding alower PPG signal quality estimate than the PPG signal quality estimateof claim
 6. 8. A method according to claim 6 the generating of a gainincludes defining the PPG signal quality estimate as a constant.
 9. Amethod according to claim 1, the element of generating two or more PPGframes of PPG signal data further includes correlating the first andsecond PPG signals with the heartbeat information; and, reinforcing eachof the first and second PPG signals that are correlated with theheartbeat information while reducing uncorrelated noise.
 10. A methodaccording to claim 1, the PPG signals including one or more of PPGsignal samples, PPG signal noise or PPG signal response time; the methodfurther including operating on one or more of the PPG signal samples,PPG signal noise, and PPG signal response time associated with thecalculating of the pulse transit time; further including one or more of:a number of the PPG signal samples included in the two or more PPGframes are adapted to reduce the PPG signal noise or decrease the PPGsignal response time; the two or more PPG frames are weighted; and, thetwo or more PPG frames are weighted and the weighting is implementedusing one or both of an IIR (infinite impulse response) or FIR (finiteimpulse response) filter.
 11. A method according to claim 1 furthercomprising one or more of: finding a sample index where the first andsecond PPG signals are at a minimum or a maximum and comparing it with aboundary of a PPG frame of the two or more PPG frames to determine thepulse transit time; or, interpolating the first and second PPG signalsusing a spline or polynomial fit around minimum or maximum values,allowing a minimum or a maximum to be determined; or, comparing one ofthe PPG frames of the two or more PPG frames to a reference frametemplate, shifting an average PPG frame with respect to the referenceframe template; finding indication of a shift of the pulse transit timewith a highest correlation between an average PPG frame and thereference frame template; further including: the reference frametemplate including a predetermined signal, or the reference frametemplate being adapted by using a long-term frame average with the pulsetransit time.
 12. A method according to claim 1 comprising performing aPPG signal quality estimate; and optionally also generating a gain foreach PPG frame of the two or more PPG frames from the PPG signal qualityestimate in conjunction with the heartbeat information; and, definingthe creating a time-concordance average frame including one or both ofthe PPG signal quality estimate and gain information with a PPG frame ofthe two or more PPG frames.
 13. A method according to claim 1, theelement of generating two or more PPG frames of PPG signals furtherincludes: reinforcing each of the PPG signals that are with theheartbeat information while reducing uncorrelated noise.
 14. A methodaccording to claim 1, the PPG signals including one or more of PPGsignal samples, PPG signal noise or PPG signal response time; the methodfurther including operating on one or more of the PPG signal samples,PPG signal noise, and PPG signal response time associated with thecalculating off pulse transit time; further including one or more of: anumber of the PPG signal samples included in the two or more PPG framesare adapted to reduce the PPG signal noise or decrease the PPG signalresponse time; the two or more PPG frames are weighted; and, the two ormore PPG frames are weighted and the weighting is implemented using oneor both of an IIR (infinite impulse response) or FIR (finite impulseresponse) filter.
 15. A method according to claim 1 further comprisingone or more of: finding a sample index where the first and second PPGsignals are at a minimum or a maximum and comparing it with a boundaryof a PPG frame of the two or more PPG frames to determine the pulsetransit time; or, interpolating the first and second PPG signals using aspline or polynomial fit around the minimum or the maximum values,allowing a minimum or a maximum to be determined; or, comparing a PPGframe of the two or more PPG frames to a reference frame template,shifting an average PPG frame is shifted with respect to the referenceframe template; finding indication of a shift of the pulse transit timewith the highest correlation between an average PPG frame and thereference frame template; further including: the reference frametemplate including a predetermined signal, or the reference frametemplate being allowed to adapted by using a long-term frame averagewith the pulse transit time.